Structural characteristics of antibacterial bioresorbable phosphate glass

Neutron diffraction with isotopic substitution has been used to probe the local environment of silver in a melt-quench derived bioresorbable phosphate glass. Samples enriched with Ag-107 and Ag-109 were prepared and neutron diffraction data collected. A first-order difference was taken between the data sets to give detailed information about the silver environment in the glass matrix. The measured Ag-O correlation has three components in the first coordination shell at 2.28 angstrom, 2.51 angstrom, and 2.58 angstrom with coordination numbers of 2.1,23, and 1.1, respectively, consistent with silver occupying a distorted octahedral environment. These results have been correlated with those from Ag K-edge X-ray absorption near-edge spectroscopy measurements. The results suggest that the addition of silver to the (CaO)(0.3)(Na2O)(0.2)(P2O5)(0.5) system has a significant effect on the host phosphate network, with shorter and more branched chains replacing the long chains and rings normally associated with the metaphosphate composition.